The present invention relates to an ink-jet head driving device for simultaneously driving a line of ink chambers to pint dots with ink drops ejected therefrom.
A conventional ink-jet printer performs printing using a print head having a plurality of ink chambers separated from each other by partitions made of, e.g., electrostrictive members. This print head ejects ink from an ink-jet nozzle upon changes in pressure of each ink chamber caused by vibration of the partitions. This print head is difficult to avoid mutual interference of adjacent ink chambers when the partitions simultaneously vibrate for the ink chambers in order to print dots of the same tone-level. This mutual interference does not allow the pressure of each ink chamber to change in the same manner as when corresponding partitions vibrate. Resultant variations in the ejected amount of ink make the print quality unstable.
A solution of this problem is disclosed in, e.g., Jpn. Pat. Appln. KOKAI Publication No. 62-116154. In this publication, each driver for an ink chamber receives an energization signal supplied to itself and, as correction signals via resistors, energization signals supplied to drivers for adjacent ink chambers driven at the same time as the target ink chamber. The driver corrects the supplied energization signal on the basis of the energization signals supplied via the resistors. More specifically, the voltage level of the correction signals are set by the resistors to represent interference pressure generated in the adjacent ink chambers. The target ink chamber is driven by an energization signal of a voltage level decreased according the voltage levels of the correction signals in the driver.
According to the driving technique of this publication, however, each ink chamber is driven without considering any interference pressure from ink chambers other than adjacent ink chambers, and the correction amount of the energization signal is fixed by the resistance value of each resistor. Therefore, this technique is difficult to control the ink ejection amount of a line print head with high precision in multi-tone printing.
It is an object of the present invention to provide an ink-jet head driving device capable of easily considering interference from ink chambers other than adjacent ink chambers.
According to the present invention, there is provided an ink-jet head driving device for an ink-jet head having a line of ink chambers, comprising a reception unit for receiving dot data corresponding to each ink chamber of the print head, a decoding unit for selectively decoding (j+k)-bit data made up of received j-bit dot data (jxe2x89xa71) of a target ink chamber and k-bit dot data (kxe2x89xa71) of neighboring ink chambers, an input unit for inputting a plurality of energization signals, and a selection unit for selecting one energization signal from the plurality of energization signals, wherein the selection unit is arranged to determine an energization signal to be selected based on a decoding result of the decoding and to drive the target ink chamber with a waveform obtained by the energization signal selected thereby.
In this ink-jet head driving device, decoding is performed on the basis of dot data for each target ink chamber and dot data for ink chambers neighboring to the target ink chamber. That is, ink chambers other than the ink chambers next to the target ink chamber can be easily considered to drive the target ink camber, and the ink ejection amount of each ink chamber can be controlled with high precision. This realizes stable print quality.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.